<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        var time = prompt('请输入一个0~59之间的数字');
        var result = time < 10 ? '0' + time : time;
        console.log(result);
        
    </script>
</head>
<body>
    
</body>
</html>